This year I have finally purchases a foxpro firestorm and have had great success so far, calling in at least one fox on every stand i've set up. My two go-to sounds have been the bay-bee cottontail and the vole squeeks, but I have also had luck on eastern cottontail and adult cottontail.
When setting up i usually start out with the bay bee cottontail and play that until the 12 minuet mark. So far this year most of the red fox have came in under 4 mins, or between the 8-10 minuet mark with the bay bee cottontail. While the majority of the fox have charged the call without stopping, i've had a few hang up around the 150-200 yd mark. When this happens i switch to the vole squeeks, which is essentually the same thing as a self produced lip squeek that everyone is familiar with. This nearly always succeeds in bringing them into shotgun range.
One thing that you should always remember is to not give up on the stand after you shoot or miss a fox. Three times this year i have sat for an additional five minuets after shooting, and inturn ended up calling in another set of eyes. I set my fox bang to vole squeeks for situations like these.
Feel free to reply with any sounds and strategies that you have found successfull this year.